Depression is a serious mental illness that can negatively impact your mood, feelings, actions, perceptions and self-esteem. Depression can be treated with therapy and/or medication. Depression is incredibly common amongst our society, although it is often misunderstood. Depression is an illness that can impact a person's ability to function or perform at work and everyday life. Symptoms of depression include: increased feelings of sadness; loss of interest in activities that one used to enjoy, changes in appetite or weight; changes in sleep patterns; loss of energy or fatigue; feelings of worthlessness and guilt; difficulty thinking or making decisions; thoughts of death or suicide. One in six people will experience depression in their lifetime; depression can occur anytime; it is common to first appear in an individual’s late teens to mid-twenties. Several elements contribute to the occurrence of depression: biochemistry, genetics, personality, past life experiences, and environmental factors all play a role.